The present invention relates to a roofing system of the type wherein a single ply roofing membrane of rubber or the like is used as the top roof layer. More specifically, the present invention is related to an improvement in such a roofing system for fastening the roof membrane in position on a roof structure.
Applicant's prior patent, U.S. Pat. No. 4,162,597, discloses and claims an insulation block and mounting means therefore which utilizes bonding pads or plates of masonite or the like disposed at the intersections of insulation boards. These bonding plates serve to hold the insulation boards in position on the roof structure. These bonding plates also serve as adhesive accommodating surfaces for holding adhesive which is then adhered to the underside of an overlying roofing membrane.
In commercial practice of the plate bonded system according to applicant's above-mentioned U.S. Pat. No. 4,162,597, EPDM rubber membrane is adhered to the bonding plates by a contact adhesive applied to both the bonding plates and the rubber membrane. This contact adhesive must first be applied to both the bonding plates and the rubber. The rubber and plates can only be adhered to one another after a certain adhesive drying time, depending upon the ambient weather conditions.
Applicant and applicant's company, Kelly Energy Systems, Inc. of Waterbury, Conn., has made and distributed a few hard masonite fiberboard bonding plates with adhesive applied by way of unreinforced gum tape strips. These unreinforced gum tape stripped bonding plates where utilized in a few mobile home roof applications. These unreinforced gum tape stripped bonding plates simplified somewhat the roof installation steps as compared to the above-mentioned contact adhesive systems where adhesive was applied to both the EPDM rubber and the masonite or plastic plates on the roof construction site.
However, since the masonite bonding plates experience delamination under certain wind load and ambient environment conditions that might occur on a roof, these unreinforced gum tape masonite installations may not perform sufficiently well in large scale commercial roof applications. For example, it is very difficult to avoid that a large scale flat commercial roof of 50,000 square feet or more will experience substantial water condensation under the rubber membrane, thus leading to potential bonding plate delamination problems with masonite bonding plates or the like. Further, in contrast to small mobile home roofs which can be covered by a single factory prepared sheet of EPDM rubber, these large commercial roofs normally require on site "field" seaming of the EPDM rubber sheets. These field seams or splices are subject to greater danger of leakage than are the factory prepared splices or seams, thereby increasing the instances of actual water leakage through the rubber roof into the space where the bonding plates are located.
The present invention is specifically directed to an improved arrangement of bonding plates for use with the system of the type disclosed and claimed in this U.S. Pat. No. 4,162,597. The present invention is also specifically directed to improved bonding plate constructions as compared to the above-noted non-reinforced gum tape stripped masonite plates.
According to the present invention, the bonding plates are provided with adhesive at their upper surfaces and this adhesive is covered by release paper. With the arrangement of the present invention, the adhesive is applied under factory controlled conditions and therefore can be applied uniformally and consistently from bonding plate to bonding plate. The installation at the roof site is simplified as compared with the prior contact adhesive arrangement since the workmen need only to remove the release paper and roll the prepared sections of rubber membrane over the top of the bonding plates. The bonding plates are mechanically attached to the underlying roof structure by screws or the like.
In certain preferred embodiments utilizing masonite bonding plates, or other bonding plates with similar delamination characteristics, the present invention contemplates the use of gum tape with scrim fiber reinforcement. These embodiments exhibit the advantages of the economically reasonable and readily available hard masonite board material with the reinforced gum tape overlapping from the top to the bottom edge of the plates to minimize the danger of rubber membrane release due to delamination of the plates.
Other preferred embodiments of the invention utilize non-delaminating material bonding plates made of materials such as Type-2 Nylon combined with two-sided adhesive gum tape that need not scrim or fabric reinforced in all cases. The Type-2 Nylon is advantageous in that it does not experience unacceptable plasticisor migration and eventual reduction in structural integrity that is expierenced by many other plastic materials. The Type-2 Nylon will not delaminate under the normal in-use ambient conditions under an EPDM roof membrane. Thus, even if these plates get wet, they will not delaminate.
The novel bonding plates of the present invention minimize the amount of adhesive that is required since there is no spillage of adhesive and the quantity of adhesive can be precisely controlled from plate to plate to be sufficient for adhering the roof mambrane in position. In especially preferred embodiments of the invention, the top surface of the bonding plates are provided with adhesive only at spaced apart strips. Since a certain minimum sized bonding plate is required on most roof installations to hold the insulation boards down and in position in the recommended patterns and since it has been determined that the entire surface of such plates need not be covered with adhesive to hold the rubber membrane, the application of adhesive in spaced apart strips optimizes the operation of the bonding plate to both hold the insulation boards in position and adhere the rubber membrane in position.
In certain preferred embodiments, the adhesive applied to the bonding plates is in the form of a two-sided gum tape, a form which is especially adaptable to the strip application of adhesive at the top surface of the bonding plate. In the masonite bond plate embodiments, the two-sided gum tape, especially fabric scrim reinforced tape, is especially advantageous in preventing delamination when placed so as to effectively overlap the plate from top to bottom.
In certain other contemplated, preferred embodiments the upper surface of the bonding plates are completely covered with preapplied adhesive. Also, embodiments with partial adhesive coverings other than strip shaped are contemplated for certain installations.
In certain preferred embodiments, the release paper for each bonding plate is formed in two separate pieces which are folded over one another along their adjoining edge so as to facilitate easy manual removal of the release paper. In order to assure that the release paper and adhesive strips stay in position on the relatively thin bonding plates during shipment and storage and in order to effectively anchor the strips to the plates and reinforce the plates against delamination, a small end portion of the adhesive strips is also extended to the bottom side of the bonding plates along the edges. In assembly on a roof structure, the release paper portions connected at the bottom of the bonding plate need not be removed and the release paper can simply be folded back away from the top surface, thus advantageously simplifying the assembly. The fastener screw or the like rigidly holds the center part of the bonding plate in position on the roof structure and the edge portions can flex upwardly during wind uplift conditions.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings, which show for purposes of illustration only, several embodiments constructed in accordance with the present invention.